Soil moisture shortage caused by high temperature and little rain
According to the monitoring of soil moisture, the soil cultivation layer in Chongqing has reached the moderate drought level, among which, the soil drought in 15 districts and counties including Qianjiang and Banan has reached the severe drought level. On August 17, a reporter from Science and Technology Daily learned about this situation from a special press conference on Chongqing’s high temperature and drought relief work in 2022. Affected by the continuous high temperature and low rainfall, some areas of Anhui, Hubei, Shaanxi and other provinces have also experienced soil moisture shortage recently.
What is lack of moisture? Moisture is divided into five grades
“Moisture refers to the humidity of the soil suitable for seed germination and crop growth. The condition of soil moisture is also called moisture.” Li Chunlei, chief of the Hydrology Station of Chongqing Water Resources Bureau, said that moisture is an important monitoring indicator for drought conditions, mainly reflecting the soil moisture content.
According to the relative soil humidity, the moisture content is divided into five grades: the soil relative humidity of the ploughing layer is greater than or equal to 90%, which is too wet, the humidity between 60% and 90% is suitable, the humidity between 50% and 60% is mild drought, and the humidity in the 40%-50% is moderate drought, humidity is 30%-40% is severe drought.
“We have more than 200 monitoring stations in the city. The earliest forecast of mild moisture content was on July 11, and the moisture content has gradually increased since August.” Li Chunlei said that the core reasons for the lack of moisture are the lack of effective rainfall and the long duration of high temperature. This leads to a gradual increase in soil evaporation and a decrease in soil water content.
It is understood that since July 1, the temperature in Chongqing has been significantly higher and the precipitation has been significantly lower. The highest temperature in 9 districts and counties has broken the local historical high temperature record. In the same period, the number was 90% lower, and 881,000 people in 33 districts and counties were affected, and 300,000 people needed life assistance due to drought. According to monitoring, 67.9% of the cultivated layers of soil moisture observation stations have reached moderate to severe drought.
“Lack of moisture is drought.” Xie Deti, a professor and doctoral supervisor at the School of Resources and Environment of Southwest University, said that if there is a continued severe lack of moisture, agricultural drought may occur. If the drought lasts for a long time, it may lead to reduced crop yields or even no harvest.
In addition to rain, there are other ways to face lack of moisture
“The best way to solve the lack of moisture is to replenish water, but in the weather with continuous high temperature and no rainfall, the test is the construction of farmland infrastructure.” Xie Deti said that the construction of water conservancy infrastructure can help farmland to quickly discharge excess water when there is a lot of water, Timely delivery of water when needed. Standardized farmland construction is to build a modern farmland that is suitable for machine and ploughing, capable of drainage and irrigation, high yield and stable yield, and guaranteed income under drought and flood by increasing the size, water, road, and soil.
“We found after inspection that continuous high temperature and drought have little impact on Chongqing’s rice and other staple crops.” said Chen Chang, the leader of the science and technology team sent by the Ministry of Agriculture and Rural Affairs to Chongqing to guide the high temperature and drought to protect autumn crops and the deputy director of the Institute of Plant Protection, Chinese Academy of Agricultural Sciences. , Chongqing’s rice harvest time is earlier, and thanks to the construction of water conservancy facilities in Chongqing, irrigation water is guaranteed even if the harvest is later. At present, economic crops such as vegetables and citrus are more affected. In this regard, the team has given guidance on moisture conservation and sun protection. Of course, the best way to relieve moisture is rainfall.
“Generally speaking, most areas can maintain a tight balance between supply and demand, but there is a shortage of water supply in some areas.” Ren Lijuan, member of the party group and deputy director of the Chongqing Municipal Water Conservancy Bureau, introduced. At present, the water supply for 415,000 people in Chongqing affected by the drought is generally guaranteed, which can be solved by means of pipe network extension, new water sources, water supply, and segmented water supply. In farmland irrigation, the role of 153 medium-sized irrigation areas and 2,442 small-sized irrigation areas has been brought into full play, with a total of 629 million cubic meters of agricultural irrigation water and 4.366 million mu of irrigated farmland.
“According to the latest meteorological data, from August 30th to September 1st and from September 8th to September 9th, Chongqing has a relatively obvious cooling and rainfall process, and the high temperature weather will gradually ease.” Member of the party group and deputy of the Chongqing Meteorological Bureau Director Yang Zhi introduced that there was a weak rainfall process around the 25th of this month, and the high temperature weakened. The city’s 266 weather-affected operation sites, 107 anti-aircraft artillery pieces, 96 rockets and nearly 600 operators have made preparations for artificial precipitation. Once there is an opportunity for operation, artificial precipitation will be carried out in a timely manner to cool down, so as to alleviate the high temperature and drought.